This invention generally relates to unicompartmental knee arthroplasty surgical operations using systems and processes for tracking anatomy, implements, instrumentation, trial implants, implant components and virtual constructs or references, and rendering images and data related to them. Anatomical structures and such items may be attached to or otherwise associated with fiducial functionality, and constructs may be registered in position using fiducial functionality whose position and orientation can be sensed and tracked by systems and according to processes of the present invention in three dimensions in order to perform unicompartmental knee arthroplasty. Such structures, items and constructs can be rendered onscreen properly positioned and oriented relative to each other using associated image files, data files, image input, other sensory input, based on the tracking. Such systems and processes, among other things, allow surgeons to navigate and perform unicompartmental knee arthroplasty using images that reveal interior portions of the body combined with computer generated or transmitted images that show surgical implements, instruments, trials, implants, and/or other devices located and oriented properly relative to the body part. Such systems and processes allow, among other things, more accurate and effective resection of bone, placement and assessment of trial implants and joint performance, and placement and assessment of performance of actual implants and joint performance.
Knee arthroplasty is a surgical procedure in which the articular surfaces of the femur, tibia and patella are cut away and replaced by metal and/or plastic prosthetic components. The goals of knee arthroplasty include resurfacing the bones in the knee joint and repositioning the joint center on the mechanical axis of the leg. Knee arthroplasty is generally recommended for patients with severe knee pain and disability caused by damage to cartilage from rheumatoid arthritis, osteoarthritis or trauma. It can be highly successful in relieving pain and restoring joint function.
More than 95% of knee arthroplasties performed in the United States are tricompartmental knee arthroplasties (xe2x80x9cTKAxe2x80x9d), which involves the replacement of all the articular surfaces of the knee joint. TKA is performed when arthritis or trauma has affected two or more of the three compartments of the knee: medial compartment (toward the body""s central axis), lateral compartment (away from the body""s central axis), and patello-femoral compartment (toward the front of the knee).
The remaining knee arthroplasties are unicompartmental knee arthroplasties (xe2x80x9cUKAxe2x80x9d). UKA involves the replacement of the articular surfaces of only one knee compartment, usually the medial compartment. UKA is an attractive surgical treatment for patients with arthritis in only one compartment and with a healthy patella.
UKA has several advantages over TKA. UKA allows the preservation of both cruciate ligaments, while the anterior cruciate ligament is usually removed in TKA. Preservation of the ligaments provides greater stability to the joint after surgery. UKA also allows for preservation of more bone stock at the joint, which will be beneficial if revision components must be placed. Finally, UKA is less invasive than TKA because UKA requires smaller resections and components.
In spite of these advantages, there continue to be problems in UKA performance. A leading cause of wear and revision in prosthetics such as knee implants, hip implants and shoulder implants is less than optimum implant alignment. In a UKA, for example, current instrument design for resection of bone limits the alignment of the femoral and tibial resections to average values for varus/valgus flexion/extension, and external/internal rotation. Additionally, surgeons often use visual landmarks or xe2x80x9crules of thumbxe2x80x9d for alignment which can be misleading due to anatomical variability. Intramedullary referencing instruments also violate the femoral and tibial canal. This intrusion increases the risk of fat embolism and unnecessary blood loss in the patient. Surgeons also rely on instrumentation to predict the appropriate implant size for the femur and tibia instead of the ability to intraoperatively template the appropriate size of the implants for optimal performance. Another challenge for surgeons is soft tissue or ligament balancing after the bone resections have been made. Releasing some of the soft tissue points can change the balance of the knee; however, the multiple options can be confusing for many surgeons. Although much of the bone stock remains after UKA, if a revision is necessary, many of the visual landmarks are no longer present, making alignment and restoration of the joint line difficult.
The present invention is applicable not only for knee repair, reconstruction or replacement surgery, but also repair, reconstruction or replacement surgery in connection with any other joint of the body as well as any other surgical or other operation where it is useful to track position and orientation of body parts, non-body components and/or virtual references such as rotational axes, and to display and output data regarding positioning and orientation of them relative to each other for use in navigation and performance of the operation.
Systems and processes according to one embodiment of the present invention use position and/or orientation tracking sensors such as infrared sensors acting stereoscopically or otherwise to track positions of body parts, surgery-related items such as implements, instrumentation, trial prosthetics, prosthetic components, and virtual constructs or references such as rotational axes which have been calculated and stored based on designation of bone landmarks. Processing capability such as any desired form of computer functionality, whether standalone, networked, or otherwise, takes into account the position and orientation information as to various items in the position sensing field (which may correspond generally or specifically to all or portions or more than all of the surgical field) based on sensed position and orientation of their associated fiducials or based on stored position and/or orientation information. The processing functionality correlates this position and orientation information for each object with stored information regarding the items, such as a computerized fluoroscopic imaged file of a femur or tibia, a wire frame data file for rendering a representation of an instrumentation component, trial prosthesis or actual prosthesis, or a computer generated file relating to a rotational axis or other virtual construct or reference. The processing functionality then displays position and orientation of these objects on a screen or monitor, or otherwise. Thus, systems and processes according to one embodiment of the invention can display and otherwise output useful data relating to predicted or actual position and orientation of body parts, surgically related items, implants, and virtual constructs for use in navigation, assessment, and otherwise performing surgery or other operations.
As one example, images such as fluoroscopy images showing internal aspects of the femur and tibia can be displayed on the monitor in combination with actual or predicted shape, position and orientation of surgical implements, instrumentation components, trial implants, actual prosthetic components, and rotational axes in order to allow the surgeon to properly position and assess performance of various aspects of the knee joint being repaired, reconstructed or replaced. The surgeon may navigate tools, instrumentation, trial prostheses, actual prostheses and other items relative to the femur and tibia in order to perform UKA""s more accurately, efficiently, and with better alignment and stability.
Systems and processes according to the present invention can also use the position tracking information and, if desired, data relating to shape and configuration of surgical related items and virtual constructs or references in order to produce numerical data which may be used with or without graphic imaging to perform tasks such as assessing performance of trial prosthetics statically and throughout a range of motion, appropriately modifying tissue such as ligaments to improve such performance and similarly assessing performance of actual prosthetic components which have been placed in the patient for alignment and stability.
Systems and processes according to the present invention can also generate data based on position tracking and, if desired, other information to provide cues on screen, aurally or as otherwise desired to assist in the surgery such as suggesting certain bone modification steps or measures which may be taken to release certain ligaments or portions of them based on performance of components as sensed by systems and processes according to the present invention.
According to a preferred embodiment of systems and processes according to the present invention, at least the following steps are involved:
1. Obtain appropriate images such as fluoroscopy images of appropriate body parts such as femur and tibia, the imager being tracked in position via an associated fiducial whose position and orientation is tracked by position/orientation sensors such as stereoscopic infrared (active or passive) sensors according to the present invention.
2. Register tools, instrumentation, trial components, prosthetic components, and other items to be used in surgery, each of which corresponds to a fiducial whose position and orientation can be tracked by the position/orientation sensors.
3. Locating and registering body structure such as designating points on the femur and tibia using a probe associated with a fiducial in order to provide the processing functionality information relating to the body part such as rotational axes.
4. Navigating and positioning instrumentation such as cutting instrumentation in order to modify bone, at least partially using images generated by the processing functionality corresponding to what is being tracked and/or has been tracked, and/or is predicted by the system, and thereby resecting bone effectively, efficiently and accurately.
5. Navigating and positioning trial components such as femoral components and tibial components, some or all of which may be installed using impactors with a fiducial and, if desired, at the appropriate time discontinuing tracking the position and orientation of the trial component using the impactor fiducial and starting to track that position and orientation using the body part fiducial on which the component is installed.
6. Assessing alignment and stability of the trial components and joint, both statically and dynamically as desired, using images of the body parts in combination with images of the trial components while conducting appropriate rotation, anterior-posterior drawer and flexion/extension tests and automatically storing and calculating results to present data or information which allows the surgeon to assess alignment and stability.
7. Releasing tissue such as ligaments if necessary and adjusting trial components as desired for acceptable alignment and stability.
8. Installing implant components whose positions may be tracked at first via fiducials associated with impactors for the components and then tracked via fiducials on the body parts in which the components are installed.
9. Assessing alignment and stability of the implant components and joint by use of some or all tests mentioned above and/or other tests as desired, releasing tissue if desired, adjusting if desired, and otherwise verifying acceptable alignment, stability and performance of the prosthesis, both statically and dynamically.
This process, or processes including it or some of it may be used in any total or partial joint repair, reconstruction or replacement, including knees, hips, shoulders, elbows, ankles and any other desired joint in the body.
Systems and processes according to the present invention represent significant improvement over other previous systems and processes. For instance, systems which use CT and MRI data generally require the placement of reference frames pre-operatively which can lead to infection at the pin site. The resulting 3D images must then be registered, or calibrated, to the patient anatomy intraoperatively. Current registration methods are less accurate than the fluoroscopic system. These imaging modalities are also more expensive. Some xe2x80x9cimagelessxe2x80x9d systems, or non-imaging systems, require digitizing a large number of points to define the complex anatomical geometries of the knee at each desired site. This can be very time intensive resulting in longer operating room time. Other imageless systems determine the mechanical axis of the knee by performing an intraoperative kinematic motion to determine the center of rotation at the hip, knee, and ankle. This requires placement of reference frames at the iliac crest of the pelvis and in or on the ankle. This calculation is also time consuming at the system must find multiple points in different planes in order to find the center of rotation. This is also problematic in patients with pathologic conditions. Ligaments and soft tissues in the arthritic patient are not normal and thus will give a center of rotation that is not desirable for normal knees. Robotic systems require expensive CT or MRI scans and also require pre-operative placement of reference frames, usually the day before surgery. These systems are also much slower, almost doubling operating room time and expense.
None of these systems can effectively track femoral and/or tibial trials during a range of motion and calculate the relative positions of the articular surfaces, among other things. Also, none of them currently make suggestions on ligament balancing, display ligament balancing techniques, or surgical techniques. Additionally, none of these systems currently track the patella.
An object of certain aspects of the present invention is to use computer processing functionality in combination with imaging and position and/or orientation tracking sensors to present to the surgeon during surgical operations visual and data information useful to navigate, track and/or position implements, instrumentation, trial components, prosthetic components and other items and virtual constructs relative to the human body in order to improve performance of a repaired, replaced or reconstructed knee joint.
Another object of certain aspects of the present invention is to use computer processing functionality in combination with imaging and position and/or orientation tracking sensors to present to the surgeon during surgical operations visual and data information useful to assess performance of a knee and certain items positioned therein, including components such as trial components and prosthetic components, for stability, alignment and other factors, and to adjust tissue and body and non-body structure in order to improve such performance of a repaired, reconstructed or replaced knee joint.
Another object of certain aspects of the present invention is to use computer processing functionality in combination with imaging and position and/or orientation tracking sensors to present to the surgeon during surgical operations visual and data information useful to show any or all of predicted position and movement of implements, instrumentation, trial components, prosthetic components and other items and virtual constructs relative to the human body in order to select appropriate components, resect bone accurately, effectively and efficiently, and thereby improve performance of a repaired, replaced or reconstructed knee joint.
Other objects, features and advantages of the present invention are apparent with respect to the remainder of this document.